Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
cham doc » cham soc, chat doc, chau doc
lang van » dang van, tang van, hoang van
cua tre » cua te, cuu tre, cua triet
sang ky » sang kyo, dang ky, tang ky
tu sang » thu sang, tu san, tu lang
ve cham » va cham, ve chat, vu cham
hieu ve » hieu va, hieu van
van hoi » van hoa, van hoc, van hoe
ky lang » ky nang, ky dang, ky tang
dan vi » doan vi, dan va, gan vi
doc ca » doc cao, doc cua, doc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sang ky lang van hoi. hieu ve cham doc ca ((dan vi) OR (don vi)) ((cua tre) or (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sang ky lang van hoi. hieu ve cham doc ca ((dan vi) OR (don vi)) ((cua tre) OR (dau tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sang ky lang van hoi. hieu ve cham doc ca ((dan vi) OR (don vi)) ((cua tre) or (dau tren))*".